Department of Environmental Science, Zhejiang University, Hangzhou 310058, China.
Institute of Soil and Water Resources and Environmental Science, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China.
Environ Sci Technol. 2024 Aug 20;58(33):14718-14725. doi: 10.1021/acs.est.4c04690. Epub 2024 Aug 7.
Cadmium (Cd) contamination poses a significant global threat to human health, primarily through dietary intake, with rice serving as a major source. While Cd predominantly resides in bound states in soil, the physiological processes by which rice facilitates Cd absorption in the rhizosphere remain largely elusive. This study delves into the mechanisms governing Cd uptake by rice plants in the rhizosphere, emphasizing the impact of daytime and nighttime fluctuations in microenvironmental conditions. Employing a microfluidic chip setup, the research reveals that radial oxygen loss from rice roots triggers dissolution of Cd in the rhizosphere. Notably, Cd mobility exhibits distinct diurnal fluctuations, peaking at 44.0 ± 4.1 nM during the daytime and dropping to 8.3 ± 1.3 nM during the nighttime. Further investigations reveal that variations in dissolved oxygen and hydroxyl radical concentrations influence Cd release, while pH changes and microbial reduction reactions play crucial roles in Cd immobilization. These findings provide insights into the intricate processes governing Cd mobilization in the rice rhizosphere, highlighting the importance of regulating these processes for effective Cd adsorption control in rice crops and safeguarding public health.
镉（Cd）污染对人类健康构成重大全球威胁，主要通过饮食摄入，而大米则是主要来源。虽然 Cd 主要以结合态存在于土壤中，但水稻促进根际 Cd 吸收的生理过程在很大程度上仍难以捉摸。本研究深入探讨了根际中水稻吸收 Cd 的机制，强调了微环境条件日夜波动的影响。本研究采用微流控芯片装置，揭示了水稻根从径向释放氧气会触发根际中 Cd 的溶解。值得注意的是，Cd 的迁移性表现出明显的日变化，白天时峰值达到 44.0 ± 4.1 nM，夜间则降至 8.3 ± 1.3 nM。进一步的研究表明，溶解氧和羟基自由基浓度的变化会影响 Cd 的释放，而 pH 值变化和微生物还原反应则在 Cd 固定化过程中起着关键作用。这些发现深入了解了控制水稻根际中 Cd 迁移的复杂过程，强调了调控这些过程对于有效控制水稻作物中 Cd 吸附和保护公众健康的重要性。
